Metal substrate for flexible display and method of manufacturing the same

ABSTRACT

The present disclosure discloses a metal substrate for a flexible display and a method of manufacturing the same, which reduce surface roughness of the metal substrate for a flexible display. The method comprises: providing a core mold adapted for a metal substrate for a flexible display; forming an electroforming metal layer at the surface of the core mold by using the core mold as a cathode, an electroforming metal used for the metal substrate for a flexible display as an anode, and a solution of a salt of the electroforming metal as an electroforming solution, and by immerging the core mold in the electroforming solution together with the electroforming metal to carry out electroforming; peeling off the electroforming metal layer from the core mold.

BACKGROUND

Embodiments of the disclosure relate to manufacture of a flexible display, especially to a method of manufacturing a metal substrate for a flexible display and the metal substrate.

An organic light-emitting device (OLED) does not only have advantages such as active light emitting, a wide view angle, quick response and the like, but also most significantly characterized in that it can realize flexible displaying. A glass substrate is generally used in a traditional OLED. But the glass substrate has not enough flexibility, so that it is easy to crash. If the existing glass substrate is replaced with a flexible substrate, then the OLED becomes an FOLED (flexible organic light-emitting device), so that a flexible display can be manufactured. The flexible display is deformable or bendable, and is suitable for some special or important occasions, for example a display in an airplane cockpit, in which occasion by using a non-glass flexible material design, security will not be impaired during ejection parachuting.

Presently, a flexible substrate used for manufacturing a flexible display mostly includes a polymer substrate (such as a plastic substrate), a metal substrate and the like. However, the polymer substrate or metal substrate manufactured in the related art has large surface roughness. For example, even if after surface polishing treatment, the metal substrate still has a root mean square (RMS) of surface roughness up to 1000 Å (angstroms), so that a display device can not be directly manufactured at the surface of the polymer substrate or metal substrate duo to such large surface roughness.

In the related art, for no matter a polymer substrate or a metal substrate, in order to improve surface roughness, planarization treatment needs be applied to reduce surface roughness. For example, it is conventional to coat the surface with an organic material (polyimide) film, an inorganic material (SiOx) film or a complex film. But it is difficult to obtain a desirable effect with planarization because the surface roughness of the polymer substrate or metal substrate is too large. Especially, a film layer structure manufactured at the surface of the substrate can be pierced by some aiguilles at the surface of the substrate, and thereby the stability and life time of the entire flexible display are impaired, and the entire thickness of the polymer substrate or metal substrate is increased after a film layer is coated.

SUMMARY

Embodiments of the present disclosure provide a method of manufacturing a metal substrate for a flexible display and the metal substrate, which reduce surface roughness of the metal substrate for a flexible display.

An embodiment of the present disclosure provides a method of manufacturing a metal substrate for a flexible display, which comprises: providing a core mold adapted for a metal substrate for a flexible display; forming an electroforming metal layer at the surface of the core mold by using the core mold as a cathode, an electroforming metal used for the metal substrate for a flexible display as an anode, and a solution of a salt of the electroforming metal as an electroforming solution, and by immerging the core mold in the electroforming solution together with the electroforming metal to carry out electroforming; and peeling off the electroforming metal layer from the core mold.

Another embodiment of the present disclosure further provides a metal substrate for a flexible display, which is the metal substrate for a flexible display that is manufactured by the above-mentioned method of manufacturing a metal substrate for a flexible display.

In the method of manufacturing a metal substrate for a flexible display provided according to the embodiments of the present disclosure, an electroforming metal layer is formed at the surface of the core mold by immerging the core mold in the electroforming solution together with the electroforming metal to carry out electroforming, and is demolded, and then the obtained electroforming metal layer can be used as a metal substrate for a flexible display. The surface roughness of thus obtained metal substrate for a flexible display is enormously reduced, for example a root mean square (RMS) of surface roughness can be reduced to about 100 Å-50 Å, thereby decreasing the damage to a film layer structure manufactured at the surface of the metal substrate for a flexible display caused by surface aiguilles, and improving the stability and rate of finished products of a flexible display.

Further scope of applicability of the present disclosure will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present disclosure and wherein:

FIG. 1 is a diagram showing the result of the surface roughness of the metal substrate for a flexible display obtained in Example 1 of the present disclosure;

FIG. 2 is a diagram showing the result of the surface roughness of the metal substrate for a flexible display obtained in Example 2 of the present disclosure;

FIG. 3 is a diagram showing the result of the surface roughness of the metal substrate for a flexible display obtained in Example 3 of the present disclosure; and

FIG. 4 is a diagram showing the result of the surface roughness of the metal substrate for a flexible display obtained in Comparative Example.

DETAILED DESCRIPTION

The method of manufacturing a metal substrate for a flexible display and the metal substrate according to an embodiment of the present disclosure will hereafter be described in detail with reference to the accompanying figures.

A method of manufacturing a metal substrate for a flexible display of the present disclosure comprises:

Step 11, providing a core mold adapted for a metal substrate for a flexible display;

Step 12, forming an electroforming metal layer at the surface of the core mold by using the core mold as a cathode, an electroforming metal used for the metal substrate for a flexible display as an anode, and a solution of a salt of the electroforming metal as an electroforming solution and immerging the core mold in the electroforming solution together with the electroforming metal to carry out electroforming; and

Step 13, peeling off the electroforming metal layer from the core mold, and using the obtained peeled electroforming metal layer as a metal substrate for a flexible display.

In the method of manufacturing a metal substrate for a flexible display according to the present embodiment, an electroforming metal layer is formed at the surface of the core mold by immerging the core mold in the electroforming solution together with the electroforming metal to carry out electroforming, and is demolded, and then the electroforming metal layer obtained after demolding is used as a metal substrate for a flexible display. Thus the surface roughness of the obtained metal substrate for a flexible display is enormously reduced, for example, a root mean square (RMS) of the surface roughness can be reduced to about 100 Å-50 Å, thereby decreasing the damage to a film layer structure manufactured at the surface of the metal substrate for a flexible display caused by surface aiguilles, and improving stability and rate of finished products of a flexible display.

The detailed process of the method of manufacturing a metal substrate for a flexible display will hereafter be described. The detailed process includes: the following steps.

Step 21, providing a core mold adapted for a metal substrate for a flexible display.

Said core mold substrate adapted for a metal substrate for a flexible display refers to a core mold substrate adapted for a metal substrate for a flexible display in terms of size, material, or the like. For example, a core mold substrate with a size of the same as or slightly greater than a metal substrate for a flexible display can be used. In the embodiment of the present disclosure, said core mold substrate can be a stainless steel substrate with a thickness of 0.04 mm, wherein the material of the stainless steel substrate can be a stainless steel with a steel grade of SUS304.

Step 22, immerging the core mold substrate in a degreasing agent to carry out chemical degreasing.

In order to deposit the electroforming metal at the surface of said core mold substrate better, the surface of the core mold substrate needs to be kept clean without any greasy impurities. For this purpose, said core mold substrate may be immerged in a degreasing agent to carry out chemical degreasing. Particularly, for example, the core mold substrate is immerged in a degreasing agent at a temperature of 50° C. for 30 minutes to carry out chemical degreasing. The components of the degreasing agent and contents thereof in term of weight ratio are as follows: sodium hydroxide:sodium carbonate:trisodium phosphate=10:5:4.

Step 23, cleaning the core mold substrate after the chemical degreasing.

In this step, the chemical degreased core mold substrate may be rinsed with water, so that the residual degreasing agent on the surface of the core mold substrate can be rinsed clean. For example, the step may include:

Step 231, firstly, the chemical degreased core mold substrate is immerged in hot water at a temperature of 50° C. or above to be rinsed with hot water. In general, the solvability of material in high temperature hot water is better than the solvability of material in low temperature cold water, and therefore a better cleaning effect may be achieved with hot water.

Step 232, then, the hot water rinsed core mold substrate is immerged in cold water at room temperature to be rinsed with cold water, so as to further clean the core mold substrate.

It will be understood that, other embodiments of the present disclosure are not limited with respect to the step 23 described here, for example, step 23 may only include the step of rinsing with hot water, or may only include the step of rinsing with cold water.

Step 24, drying the cleaned core mold substrate, to obtain a core mold adapted for a metal substrate for a flexible display.

In this step, various drying methods may be used to dry the cleaned core mold substrate. For example, methods such as air drying, heat evaporation or the like may be used.

With the above steps 21-24, a core mold adapted for a metal substrate for a flexible display has been manufactured. How to electroform to form an electroforming metal layer at the surface of the core mold will hereafter be described with more details.

Step 25, forming an electroforming metal layer on the surface of the core mold by using the core mold as a cathode, an electroforming metal used for the metal substrate for a flexible display as an anode, and a solution of a salt of the electroforming metal as an electroforming solution, and by immerging the core mold in the electroforming solution together with the electroforming metal to carry out electroforming.

Particularly, in order that the electroforming solution around the core mold has a high concentration and to increase a reaction rate, the electroforming solution is jetted to the surface of the core mold after immerging the core mold in the electroforming solution together with the electroforming metal and during the electroforming. For example, the electroforming solution may be continuously fed to an electroforming groove containing the electroforming solution through a liquid conveying pipe, and during this process, the liquid conveying pipe may be arranged facing toward the core mold, so that the electroforming solution is directly jetted onto the surface of the core mold.

While the electroforming solution is being jetted to the surface of the core mold, the electroforming solution around the core mold may also be stirred. By stirring the electroforming solution around the core mold, the polarization of the electroforming solution around the core mold can be improved, and the concentration of the electroforming solution around the core mold can be kept uniform. For example, in this step, the electroforming solution around the core mold may be stirred by way of moving said core mold. Of course, stirring may be carried out by a separate stirring rod or the like.

It will be understood that, in other embodiments of the present disclosure, it is not limited to stir the electroforming solution around the core mold while jetting the electroforming solution toward the surface of the core mold, so as to improve the electroform effect. During the electroforming, improvement of the electroform effect may be realized by only jetting the electroforming solution toward the surface of the core mold, or by only stirring the electroforming solution around the core mold.

Furthermore, one thing to be noticed is that metals such as nickel, copper, iron and the like may be used as the electroforming metal in respective embodiments of the present disclosure, and the thus formed metal substrate for a flexible display may be a nickel metal substrate, a copper metal substrate, and an iron metal substrate. In this step, a composition of the electroforming solution is explained with a nickel sulfamate electroforming solution used for electroforming nickel as an example. For instance, the components of the electroforming solution and contents thereof are as follows:

nickel sulfamate 54.0 g/l~63.0 g/l nickel chloride 140.0 g/l~180.0 g/l benzoic sulfimide 0.5 g/l~1.0 g/l sodium lauryl sulfate 0.05 g/l~1.0 g/l  1,4-butanediol 0.2 g/l~0.6 g/l boric acid 30.0 g/l~45.0 g/l

The nickel sulfamate in the electroforming solution may be obtained from a nickel sulfamate concentrated solution of 180 g/l, and in this case, the level of a nickel sulfamate concentrated solution needed in the electroforming solution may be 300.0 ml/l˜350.0 ml/l. Alternatively, nickel sulfamate in the electroforming solution may be prepared by reacting sulfamic acid with nickel or a nickel compound. Furthermore, the nickel sulfamate concentrated solution may be an aqueous or ethanol solution of nickel sulfamate. Similarly, the nickel chloride in the electroforming solution may be obtained from a nickel chloride concentrated solution of 500 g/l, and in this case the level of the nickel chloride concentrated solution needed in the electroforming solution may be 28.0 ml/l˜36.0 ml/l. Alternatively, nickel chloride in the electroforming solution may be prepared by reacting other chloride with a nickel compound. Furthermore, the nickel chloride concentrated solution may be an aqueous or ethanol solution of nickel chloride.

In order to further enhance the electroforming effect, and to make the electroforming metal deposited at the surface of the core mold neat, a filtrated electroforming solution may be used. Specifically, the filtrated electroforming solution refers to an electroforming solution which is filtrated through a filter core of 1 μm.

A PH of the electroforming solution is from 4.5 to 5.5.

A temperature of the electroforming solution is from 45° C. to 60° C.

An electric current used during the electroforming is an electric current having a current density of 2-10 A/cm².

An electrical source used during the electroforming is a high frequency pulse electrical source having a pulse frequency of 10-5000 hertz. In an example, the electrical source used during the electroforming is a high frequency pulse electrical source having a pulse frequency of 3500-5000 hertz.

After immerging the core mold in the electroforming solution together with the electroforming metal, a distance between the core mold and the electroforming metal is kept from 30 cm to 40 cm. In an example, the distance between the core mold and the electroforming metal is kept 38 cm.

With Step 25 described above, an electroforming metal layer has been formed at the surface of the core mold, and then:

Step 26, after the core mold, at the surface of which the electroforming metal layer is formed, is taken out from the electroforming solution, the electroforming metal layer is peeled from the core mold, and the peeled electroforming metal layer is used as a metal substrate for a flexible display.

The surface roughness of the obtained metal substrate for a flexible display is enormously reduced, for example a root mean square (RMS) of surface roughness may be reduced to about 100 Å-50 Å, thereby decreasing damage to a film layer structure manufactured at the surface of the metal substrate for a flexible display caused by surface aiguilles, and improving the stability and rate of finished products of a flexible display.

The method of manufacturing a metal substrate for a flexible display will hereafter be described with specific examples.

Example 1

A stainless steel substrate with a thickness of 0.04 mm and with a steel grade of SUS304 is used as the core mold substrate, which is subjected to chemical degreasing, rinsing with hot water, rinsing with cold water and air drying before electroforming, so that a core mold adapted for a metal substrate for a flexible display is obtained.

With said core mold as a cathode, a nickel metal as an anode, and an electroforming solution of nickel sulfamate as an electroforming solution, the core mold is immerged in said electroforming solution together with the nickel metal to carry out electroforming, to form a nickel metal layer at the surface of the core mold, wherein, the components of the electroforming solution and contents thereof are as follows:

a nickel sulfamate concentrated solution(180 g/l) 340.0 ml/l a nickel chloride concentrated solution(500 g/1) 30.0 ml/l benzoic sulflmide 0.8 g/l sodium lauryl sulfate 0.5 g/l 1,4-butanediol 0.4 g/l boric acid 40.0 g/l

wherein, a content of 340.0 ml/l of the nickel sulfamate concentrated solution (180 g/l) in the electroforming solution corresponds to a content of 61.2 g/l of the nickel sulfamate in the electroforming solution. A content of 30.0 ml/l of the nickel chloride concentrated solution (500 g/l) in the electroforming solution corresponds to a content of 150 g/l of the nickel chloride in the electroforming solution.

The electroforming solution is an electroforming solution that is obtained via filtration through a filtrating core of 1 μm.

A PH of the electroforming solution is 5.2.

A temperature of the electroforming solution is 55° C.

An electric current used during the electroforming is an electric current having a current density of 6 A/cm².

An electrical source used during the electroforming is a high frequency pulse electrical source having a pulse frequency of 3500-5000 hertz.

A distance between the core mold and the electroforming metal is kept 38 cm.

After the electroforming is completed, the core mold, at the surface of which an electroforming metal layer is formed, is taken out from the electroforming solution, and demolded, and the demolded electroforming metal layer is used as a metal substrate for a flexible display.

A test result of the surface roughness of the obtained metal substrate for a flexible display detected by an atomic force microscope is shown in FIG. 1. The atomic force microscope is a commonly used instrument for detecting a surface roughness of an object in the related art. As can be seen from FIG. 1, a height of the maximal aiguille at the surface is (31.74−21.66)=10.08 nm (1 nm=10 Å) in a part of a section of the metal substrate for a flexible display.

Example 2

A stainless steel substrate with a thickness of 0.04 mm and with a steel grade of SUS304 is used as the core mold substrate, which is subjected to chemical degreasing, rinsing with hot water, rinsing with cold water and air drying before electroforming, so that a core mold adapted for a metal substrate for a flexible display is obtained.

With said core mold as a cathode, a nickel metal as an anode, and an electroforming solution of nickel sulfamate as an electroforming solution, the core mold is immerged in said electroforming solution together with the nickel metal to carry out electroforming, to form a nickel metal layer at the surface of the core mold, wherein, the components of the electroforming solution and contents thereof are as follows:

a nickel sulfamate concentrated solution (180 g/l) 330.0 ml/l a nickel chloride concentrated solution (500 g/1) 28.0 ml/l benzoic sulfimide 0.6 g/l sodium lauryl sulfate 0.5 g/l 1,4-butanediol 0.2 g/l boric acid 35.0 g/l

wherein, a content of 330.0 ml/l of the nickel sulfamate concentrated solution (180 g/l) in the electroforming solution corresponds to a content of 59.4 g/l of the nickel sulfamate in the electroforming solution. A content of 28.0 ml/l of the nickel chloride concentrated solution (500 g/l) in the electroforming solution corresponds to a content of 140 g/l of the nickel chloride in the electroforming solution.

The electroforming solution is an electroforming solution that is obtained via filtration through a filtrating core of 1 μm.

A PH of the electroforming solution is 5.0.

A temperature of the electroforming solution is 55° C.

An electric current used during the electroforming is an electric current having a current density of 6 A/cm².

An electrical source used during the electroforming is a high frequency pulse electrical source having a pulse frequency of 3500-5000 hertz.

A distance between the core mold and the electroforming metal is kept 38 cm.

After the electroforming is completed, the core mold, at the surface of which an electroforming metal layer is formed, is taken out from the electroforming solution, and demolded, and the demolded electroforming metal layer is used as a metal substrate for a flexible display.

A test result of the surface roughness of the obtained metal substrate for a flexible display detected by an atomic force microscope is shown in FIG. 2. The atomic force microscope is a commonly used instrument for detecting a surface roughness of an object in the related art. As can be seen from FIG. 2, a height of the maximal aiguille at the surface is (13.39−3.13)=10.26 nm (1 nm=10 Å) in a part of a section of the metal substrate for a flexible display.

Example 3

A stainless steel substrate with a thickness of 0.04 mm and with a steel grade of SUS304 is used as the core mold substrate, which is subjected to chemical degreasing, rinsing with hot water, rinsing with cold water and air drying before electroforming, so that a core mold adapted for a metal substrate for a flexible display is obtained.

With said core mold as a cathode, a nickel metal as an anode, and an electroforming solution of nickel sulfamate as an electroforming solution, the core mold is immerged in said electroforming solution together with the nickel metal to carry out electroforming, to form a nickel metal layer at the surface of the core mold, wherein, the components of the electroforming solution and contents thereof are as follows:

a nickel sulfamate concentrated solution (180 g/l) 345.0 ml/l a nickel chloride concentrated solution (500 g/1) 35.0 ml/l benzoic sulfimide 1.0 g/l sodium lauryl sulfate 0.8 g/l 1,4-butanediol 0.5 g/l boric acid 45.0 g/l

wherein, a content of 345.0 ml/l of the nickel sulfamate concentrated solution (180 g/l) in the electroforming solution corresponds to a content of 62.1 g/l of the nickel sulfamate in the electroforming solution. A content of 35.0 ml/l of the nickel chloride concentrated solution (500 g/l) in the electroforming solution corresponds to a content of 175 g/l of the nickel chloride in the electroforming solution.

The electroforming solution is an electroforming solution that is obtained via filtration through a filtrating core of 1 μm.

A PH of the electroforming solution is 4.8.

A temperature of the electroforming solution is 55° C.

An electric current used during the electroforming is an electric current having a current density of 6 A/cm².

An electrical source used during the electroforming is a high frequency pulse electrical source having a pulse frequency of 3500-5000 hertz.

A distance between the core mold and the electroforming metal is kept 38 cm.

After the electroforming is completed, the core mold, at the surface of which an electroforming metal layer is formed, is taken out from the electroforming solution, and demolded, and the demolded electroforming metal layer is used as a metal substrate for a flexible display.

A test result of the surface roughness of the obtained metal substrate for a flexible display detected by an atomic force microscope is shown in FIG. 3. The atomic force microscope is a commonly used instrument for detecting a surface roughness of an object in the related art. As may be seen from FIG. 3, a height of maximal aiguilles at the surface is (11.13−3.92)=7.21 nm (1 nm=10 Å) in a part of a section of the metal substrate for a flexible display.

Comparative Example

A stainless steel substrate with a thickness of 0.04 mm and with a steel grade of SUS304 is used, and is subjected to chemical degreasing, rinsing with hot water, rinsing with cold water and drying. Polyimide is coated on the dried stainless steel substrate to improve the surface roughness of the stainless steel substrate, and a thickness of the polyimide is 2 μm. The polyimide is closely adhered to the stainless steel foil via baking at a high temperature of 250° C., and a metal substrate for a flexible display is obtained.

A test result of the surface roughness of the obtained metal substrate for a flexible display detected by an atomic force microscope is shown in FIG. 4. The atomic force microscope is a commonly used instrument for detecting a surface roughness of an object in the related art. As can be seen from FIG. 4, a height of the maximal aiguille at the surface is (90.78−18.55)=72.23 nm (1 nm=10 Å) in a part of a section of the metal substrate for a flexible display.

As can be seen from the results obtained from the above Examples and Comparative Example, compared with a metal substrate for a flexible display obtained by coating with an organic material(polyimide)film, an inorganic material (SiOx) film or a complex film in the related art, the surface roughness of the metal substrate for a flexible display obtained in the present examples is enormously reduced, the damage to the film layer structure manufactured at the surface of the metal substrate for a flexible display by surface aiguilles is decreased, and the stability and rate of finished products of the flexible display device are improved.

A flexible display which may be manufactured with the metal substrate for a flexible display manufactured with the method described above includes, but is not limited to, a thin film transistor liquid crystal display (TFT-LCD), a passive organic light emitting diode, an active organic light emitting diode, a thin film transistor static RAM (TFT-SRAM), a flexible electrophoretic display and the like.

In addition, embodiments of the present disclosure further provide a metal substrate for a flexible display manufactured with the method described above, which has low surface roughness, and thus makes it possible to decrease the damage to a film layer structure manufactured at the surface of the metal substrate for a flexible display caused by surface aiguilles, and to improve stability and rate of finished products of a flexible display device.

The disclosure being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure, and all such modifications as would be obvious to those skilled in the art are intended to be included within the scope of the following claims. 

1. A method of manufacturing a metal substrate for a flexible display, comprising: providing a core mold adapted for a metal substrate for a flexible display; forming an electroforming metal layer at the surface of the core mold by using the core mold as a cathode, an electroforming metal used for the metal substrate for a flexible display as an anode, and a solution of a salt of the electroforming metal as an electroforming solution, and immerging the core mold in the electroforming solution together with the electroforming metal to carry out electroforming; and peeling off the electroforming metal layer from the core mold.
 2. The method according to claim 1, wherein, after immerging the core mold in the electroforming solution together with the electroforming metal, and during the electroforming, the method further includes: jetting the electroforming solution to the surface of the core mold, and at the same time stirring the electroforming solution around the core mold.
 3. The method according to claim 1, wherein components of the electroforming solution and contents thereof include: nickel sulfamate 54.0 g/l~63.0 g/l, nickel chloride 140.0 g/l~180.0 g/l, benzoic sulfimide 0.5 g/l~1.0 g/l, sodium lauryl sulfate 0.05 g/l~1.0 g/l,  1,4-butanediol     0.2 g/l~0.6 g/l, and boric acid 30.0 g/l~45.0 g/l.


4. The method according to claim 3, wherein the electroforming solution is an electroforming solution that is obtained via filtration through a filtrating core of 1 μm, a PH of the electroforming solution is from 4.5 to 5.5, and a temperature of the electroforming solution is from 45° C. to 60° C.
 5. The method according to claim 2, wherein components of the electroforming solution and contents thereof include: nickel sulfamate 54.0 g/l~63.0 g/l, nickel chloride 140.0 g/l~180.0 g/l, benzoic sulfimide 0.5 g/l~1.0 g/l, sodium lauryl sulfate 0.05 g/l~1.0 g/l,  1,4-butanediol     0.2 g/l~0.6 g/l, and boric acid 30.0 g/l~45.0 g/l.


6. The method according to claim 5, wherein the electroforming solution is an electroforming solution that is obtained via filtration through a filtrating core of 1 μm, a PH of the electroforming solution is from 4.5 to 5.5, and a temperature of the electroforming solution is from 45° C. to 60° C.
 7. The method according to claim 1, wherein an electric current used during the electroforming is an electric current having a current density of 2-10 A/cm², and an electrical source used during the electroforming is a high frequency pulse electrical source having a pulse frequency of 10-5000 hertz.
 8. The method according to claim 2, wherein an electric current used during the electroforming is an electric current having a current density of 2-10 A/cm², and an electrical source used during the electroforming is a high frequency pulse electrical source having a pulse frequency of 10-5000 hertz.
 9. The method according to claim 1, wherein after immerging the core mold in the electroforming solution together with the electroforming metal, a distance between the core mold and the electroforming metal is kept from 30 cm to 40 cm.
 10. The method according to claim 2, wherein after immerging the core mold in the electroforming solution together with the electroforming metal, a distance between the core mold and the electroforming metal is kept from 30 cm to 40 cm.
 11. The method according to claim 1, wherein the providing of a core mold adapted for a metal substrate for a flexible display comprises: providing a core mold substrate adapted for a metal substrate for a flexible display; immerging the core mold substrate in a degreasing agent to carry out chemical degreasing; cleaning the chemical degreased core mold substrate; and drying the cleaned core mold substrate, to obtain the core mold adapted for a metal substrate for a flexible display.
 12. The method according to claim 11, wherein the immerging of the core mold substrate in the degreasing agent to carry out chemical degreasing includes: immerging the core mold substrate in the degreasing agent having a temperature of 50° C. for 30 minutes to carry out the chemical degreasing.
 13. The method according to claim 12, wherein components of the degreasing agent and contents thereof in term of weight ratio are as follows: sodium hydroxide:sodium carbonate:trisodium phosphate=10:5:4.
 14. The method according to claim 13, wherein the core mold substrate is a stainless steel substrate with a thickness of 0.04 mm.
 15. The method according to claim 2, wherein the providing of a core mold adapted for a metal substrate for a flexible display comprises: providing a core mold substrate adapted for a metal substrate for a flexible display; immerging the core mold substrate in a degreasing agent to carry out chemical degreasing; cleaning the chemical degreased core mold substrate; and drying the cleaned core mold substrate, to obtain the core mold adapted for a metal substrate for a flexible display.
 16. The method according to claim 15, wherein the immerging of the core mold substrate in the degreasing agent to carry out chemical degreasing includes: immerging the core mold substrate in the degreasing agent having a temperature of 50° C. for 30 minutes to carry out the chemical degreasing.
 17. The method according to claim 16, wherein components of the degreasing agent and contents thereof in term of weight ratio are as follows: sodium hydroxide:sodium carbonate:trisodium phosphate=10:5:4.
 18. The method according to claim 17, wherein the core mold substrate is a stainless steel substrate with a thickness of 0.04 mm.
 19. A metal substrate for a flexible display manufactured with a method according to claim
 1. 